The invention pertains to optical filters for viewing a selected object with respect to a background and eyewear that include such filters.
Individual effectiveness in performing physical tasks frequently depends upon an individual""s visual skills, such as acuity, contrast-sensitivity, and depth perception. For example, skilled crafts such as welding, cabinetmaking, and jewelry-making require accurate perception of objects. Recreational activities such as team and individual sports as well as outdoor recreational pursuits such as mountain climbing and hunting rely on visual performance. For most individuals, visual acuity is readily correctable with corrective eyewear, contact lenses, or surgical techniques. Unfortunately, such correction generally does not improve visual skills other than acuity. For many activities, enhancement of skills such as color-contrast sensitivity and depth perception beyond the normal range of vision is desirable.
For some activities, protective eyewear or other vision protection is necessary. Such vision protection typically reduces or eliminates the possibility of activity-specific injuries or activity-specific exposure to reagents, intense light fluxes, or light fluxes in particularly harmful wavelength ranges. For example, dark tinted lenses can be used to reduce exposure to intense light fluxes characteristic of welding, or goggles can be used to protect the eyes from injuries in sports such as basketball that involve risk of physical contact. While such protective eyewear can prevent eye injuries, the eyewear often interferes with or degrades various visual skills.
Stephens et al., U.S. Pat. No. 4,952,046, disclose protective eyewear based on lenses that exhibit a sharp-cut spectral transmittance that substantially eliminates all incident radiation at wavelengths shorter than 515 nm and transmits substantially all incident radiation at wavelengths greater than 636 nm. The radiation at wavelengths shorter than 515 nm that is removed by these lenses has been implicated in senile macular degeneration and snow blindness, so that these lenses provide protection against these conditions.
Specially adapted optical filters have been suggested that transmit more light at wavelengths overlapping a wavelength range in which a colored object reflects or emits light. See, for example, Moore et al., PCT App. No. PCT/US96/19761. In one example, Moore et al. suggest applying a blue dye to a transparent lens for enhanced viewing of an optic yellow tennis ball.
The eyewear of Stephens et al. and Moore et al. are intended to improve eye safety and enhance object visibility. Nonetheless, such eyewear exhibit numerous limitations and improved filters and eyewear are needed.
While prior art eyewear can provide eye protection and enhance the visibility of a colored object, such eyewear is typically unpleasant to wear because of the unnatural appearance of scenes viewed through the eyewear. For example, background surfaces can appear too dark because radiation at wavelengths reflected from background surfaces is attenuated by the eyewear. In an extreme example, a background can appear black. In addition, color rendition with such eyewear is peculiar, and users of such eyewear find the appearance of common scenes unnatural. Users of such eyewear may also experience difficulty in accurately focusing on objects, thereby affecting depth perception and timing.
Optical filters and lenses for viewing a selected object are provided that have a spectral transmittance that includes an object-contrast spectral window and a background spectral window. The object-contrast window corresponds to a spectral distribution of light reflected or emitted by the selected object. The background window includes wavelengths corresponding to radiation received from a reflective or luminous background against which the object is viewed. In alternative embodiments, the filters have spectral transmittances that include a spectral-width window. In a particular example, the background window includes a wavelength range from about 540 nm to about 560 nm or a wavelength range of from about 530 nm to about 570 nm.
In additional embodiments, the optical filters have a background window corresponding to a reflecting spectral region of vegetation. In other example filters, the object-contrast window corresponds to a fluorescence spectrum of light emitted by the object. According to additional examples, such object-contrast optical filters can include a spectral-width window configured to provide more natural appearing scenes as viewed with the filters and to provide a broader spectral bandwidth to the user""s eye. In some examples, the spectral-width window includes wavelengths greater than about 610 nm.
Eyewear for enhanced viewing of an object with respect to a background include a frame and at least one lens configured to be placed with respect to a wearer""s eyes so that the wearer looks through the lens when the eyewear is worn. The lens defines a spectral transmittance having an object-contrast window and a background window. In representative examples, the background window corresponds to a wavelength range in which vegetation is reflective. In other examples, the background window includes wavelengths between about 540 nm to about 560 nm, or other wavelength ranges.
According to additional embodiments, eyewear include a lens having an object-contrast window that preferentially transmits, reflects, or otherwise directs light corresponding to a wavelength-conversion spectral power distribution to the wearer""s eye. According to other examples, the eyewear include a lens that defines a spectral-width window.
Eyewear are provided that include an optical filter that preferentially transmits light within an object-contrast window and a background window. In some examples, the object-contrast window corresponds to an object-specific reflectance window or an object-specific wavelength-conversion window.
Natural-contrast, enhanced-visibility eyewear include a lens having a spectral transmittance that has a background window and an enhanced-visibility window. The lens is retained by a frame that situates the lens so that a wearer looks through the lens with the eyewear as worn. In representative examples, the lens is a unitary lens and is situated by the frame so that a wearer views through the lens with both eyes with the eyewear as worn.
These and other features and aspects of the invention are described below with reference to the accompanying drawings.